Netero is actually the villian of this arc if you see the King as the Hero, struggling to figure out his identity, but outside of that what makes Netero truly evil, or at the very least an anti-villian is his manipulation of a 14-16 y/o boy. Netero is too intelligent not to figure out Gon's personaility type, and after recognizing his potential its pretty obvious Netero USED Gon because he knew as Ging's son he would be able to take on Pitou, or at the very least buy him enough time to fight the King. He even says in the beginning of the arc, some people will die, or we'll have to sacrifice some individuals. Sure you can say he was doing it for the greater good, but we all knew Netero is selfish as hell, and doesn't give a shit about politics. He does things to satisfy him, and if you re-watch the arc you can see some parallels between him and Tsrennictch. Its kind of striking.

In summary I think Netero knew both Gon's mental status, and potential, and figured he'd be able to do what it takes. He even set the situation between him, and Knuckles because he wanted to fortify his resolve, and Netero knows how nen works when a person's will is in play in a nen battle. Its the reason why Kurapika destroyed Uvogin. Than they bring Kite's corpse, and parade it in front of Gon. I don't believe for a sec Netero actually thought Kite was alive. He used Gon to satisfy himself with a battle even though he's old asf. We shouldn't glorfiy old people that want to put us all in danger to satisfy themselves, even if the ends justify the means.